Fos expression in catecholaminergic medullary neurons induced by chemical stimulation of stomach projecting to the paraventricular nucleus of the hypothalamus in rats

Abstract

AIM:To determine whether medullary catecholaminergic neurons expressing Fos induced by chemical stimulation o� the stomach project to the paraventricular nucleus o� hypothalamus (PVH) in rats. METHODS:Horseradish peroxidase (HRP) was introduced stereotaxically into the PVH o� rats. Histochemical analysis o� coronal sections through the medulla were analyzed using triple-label immunohistochemistry to identi�y cells that were retrogradely labeled with HRP, Fos (ABC method), and tyrosin hydroxylase (TH) (PAP method). RESULTS:Seven kinds o� labeled neurons were �ound in the nucleus tractus solitarii (NTS), the ventrolateral medulla (VLM) and the reticular �ormation (RF) o� the medulla: Fos-like immunoreactive (FosLI) neurons, TH-like immunoreactive (TH-LI) neurons and HRP retrogradely single-labeled neurons, FosLI/HRP, FosLI/TH-LI and HRP/ TH-LI double-labeled neurons, and FosLI/HRP/TH-LI triple-labeled neurons. CONCLUSION:Ascending projections �rom the NTS, VLM and RF to the PVH might be involved in the transmitting process o� visceral noxious stimulation.